Albert Einstein (born March 14, 1879 in Ulm, Württemberg, and died April 18, 1955 in Princeton, New Jersey) was a theoretical physicist who was successively German, stateless (1896), Swiss (1901) and dual Swiss-American ( 1940).
He published his theory of special relativity in 1905, and his theory of gravitation called general relativity in 1915. He contributed greatly to the development of quantum mechanics and cosmology, and received the Nobel Prize in Physics in 1921 for his explanation of the photoelectric effect. His work is particularly known to the general public for the equation E=mc2, which establishes an equivalence between the matter and the energy of a system.
He is now considered one of the greatest scientists in history, and his fame goes far beyond the scientific community. He is the personality of the 20th century according to the weekly Time.
Youth
His father, Hermann Einstein, was born on August 30, 1847 in Buchau, and died on October 10, 1902 in Milan. He married Pauline Koch (1858-1920) on August 8, 1876. Three years later, on March 14, 1879, Albert Einstein was born in their apartment in Ulm, Germany; this is their first child. The Einsteins are non-practicing Jews. His interest in science was awakened in his childhood by a compass at the age of five, and the book The Little Bible of Geometry at thirteen.
Training
Einstein presents a relatively atypical school career compared to the eminent scientists who were later his contemporaries. Very early on, the young man protested against the arbitrary power exercised by the teachers, and was therefore often depicted as a bad element, very stunned by them. Until late in his childhood, he had difficulty expressing himself. They are potentially due to the dyslexia he suffered from as a child.
He began his schooling at the Luitpold Gymnasium in Munich and was expelled at the age of 15 (his Greek teacher judging his presence incompatible with the strict discipline reigning there at the time). He has excellent results in mathematics, but refuses to learn biology and human sciences, because he does not see the point of learning disciplines that he considers already widely explored. He then considers science as the fruit of human reason and reflection. He asks his father to give him Swiss nationality, in order to join his family, who emigrated to Pavia, Italy.
At 16, he decided to join the Swiss Federal Institute of Technology in Zurich (which can be accessed without having a baccalaureate). However, he failed the entrance exam. The examiners, having discovered his potential, encourage him to present himself a second time. He then entered the Cantonal School of Aarau in Switzerland, and spent a year there to better prepare for the next exam. He finds an atmosphere more open and conducive to his learning, with students more encouraged to think for themselves than to recite lessons learned. In 1896, he passed the exam, and therefore joined the school, where he befriended the mathematician Marcel Grossmann, who would later help him in non-Euclidean geometry. There he also met Mileva Maric, his first wife. He narrowly graduated in 1900, admitting in his autobiography that he was "unable to follow classes, take notes and work on them in an academic fashion".
During this period, he deepened his self-taught knowledge by reading reference books such as those by Ludwig Boltzmann, Helmholtz and Walther Hermann Nernst. His friend Michele Besso introduced him to the ideas of Ernst Mach's Mechanics. According to several biographies, this period from 1900 to 1902 was marked by the precariousness of his situation:he applied for many jobs without being accepted. Albert Einstein's misery worries his father, who tries in vain to find him a job. Albert then resigns himself to leaving academia to find a job in the administration.
Career
In 1901, he published his first scientific article in the Annalen der Physik, and this article was dedicated to his research on capillarity.
At the end of 1902, the first of Albert Einstein's children, Lieserl, was born. Its existence has long been ignored by historians, and there is no known information about its future. Albert and Mileva married in 1903, her father finally giving her permission on his deathbed. In 1904, the couple gave birth to Hans-Albert, then in 1910 was born Eduard Einstein.
In June 1902, he was hired at the Berne Patent Office, which allowed him to live decently while continuing his work. He moved between 1903 and 1905 in the current house of Einstein. During this period, he founded the Olympia Academy with Conrad Habicht and Maurice Solovine, who would later translate his works into French. This discussion circle meets at 49 rue Kramgasse, and organizes mountain walks. Einstein shared the results of his work with Conrad Habicht and sent him the articles he published during the year 1905 (often called his annus mirabilis) concerning the foundations of special relativity, the hypothesis of quanta of light and the theory of Brownian motion, which open new avenues in research in nuclear physics, celestial mechanics, etc. The article on Brownian motion is based on work that Einstein developed later, and which culminated in his thesis, entitled Eine neue Bestimmung der Moleküldimensionen ("A new determination of molecular dimensions", in German), and his doctoral degree on January 15, 1906.
In 1909, Albert Einstein was recognized by his peers, in particular Planck and Nernst, who wished to invite him to the University of Berlin. On July 9, 1909, he was awarded an honorary doctorate by the University of Geneva7. Job vacancies are increasing. In 1911, he was invited to the first Solvay Congress in Belgium, which brought together the most famous scientists. There he met, among others, Marie Curie, Max Planck and Paul Langevin. In 1913, Albert was appointed to the Prussian Academy of Sciences.
In 1914 he moved to Germany and lived in Berlin for many years. He became a member of the Royal Academy of Sciences and Letters in Berlin. The job offers he receives allow him to devote himself entirely to his research work. Mileva and Albert separate, and the latter begins dating a Berlin cousin, Elsa. At the opening of the First World War conflict, he declared his pacifist views. The city of Berlin had undertaken to provide him with a house, but Albert Einstein finally obtained land on which he had a house built at his own expense. Located in Caputh, near Lake Havelsee, the place is quiet and allows frequent sailing.
In 1916, he published a book presenting his theory of gravitation, known today as general relativity. In 1919, Arthur Eddington measured the deviation that the light of a star undergoes near the Sun, this deviation being one of the predictions resulting from this theory. This event is publicized, and Einstein undertakes from 1920 many trips around the world. In 1925, he was awarded the Copley Medal, and in 1928 he was appointed president of the League of Human Rights. In 1928, he participated in the first university course in Davos, with many other French and German intellectuals. In 1935, he was awarded the Franklin Medal.
The situation darkened in Germany in the 1920s, and he suffered attacks aimed at his Jewish origins and his pacifist opinions. Its security is threatened by the rise of nationalist movements, including that of the Nazi Party. Shortly after Hitler came to power in early 1933, he learned that his house in Caputh had been looted by the Nazis, and he decided not to return to Germany. After a short stay on the Belgian coast, he moved to the United States, where he worked at the Institute for Advanced Study in Princeton. His research aims to develop a theory unifying gravitation and electromagnetism, but without success, which perhaps diverts him from other research in more fruitful areas.
On August 2, 1939, under pressure from Eugene Wigner and Leó Szilárd, physicists from Germany, he wrote a letter to Roosevelt, which helped to initiate the Manhattan Project.
His son Eduard, suffering from possible schizophrenia, spent most of his life in a clinic in Switzerland, and his other son Hans-Albert became an engineer in California.
Death
Einstein died on April 18, 1955 from a ruptured aneurysm. A 2013 study of his brain reveals at most a hyperconnection between the two hemispheres, which is traditionally evidence of high intelligence. His ashes are scattered in an undisclosed location, in accordance with his last wishes. But, despite his will, his brain and his eyes were removed, the first by the pathologist who performed the autopsy, the second by his ophthalmologist.
Scientific work
Year 1905
The year 1905 is an exceptionally fruitful year for Einstein (it is often referred to by the Latin expression annus mirabilis), four of his articles being published in the journal Annalen der Physik:
the first article, published in March, presents a revolutionary point of view on the corpuscular nature of light, by studying the photoelectric effect. Einstein entitles it:On a heuristic point of view concerning the production and transformation of light. He relates his research on the origin of particle emissions, based on the work of Planck who, in 1900, established a formula for quantified radiation, that is to say discontinuous. Planck had been forced to approach the light radiation emitted by a hot body in a way that disconcerted him:to bring his formula into line with the experimental results, he had had to assume that the stream of particles split into blocks of energy, which he called quanta.
Although he thought that these quanta had no real existence, his theory seemed promising and several physicists worked on it. Einstein reinvests the results of Planck to study the photoelectric effect, and he concludes by stating that light behaves both as a wave and as a flow of particles. The photoelectric effect therefore provided a simple confirmation of Max Planck's quanta hypothesis. In 1920, quanta were called photons;
two months later, in May, Einstein published a second paper on Brownian motion. He explains this movement by a complete departure from the principle of entropy as stated following Newton's work on mechanical forces:according to him, molecules derive their kinetic energy from heat. This article provides theoretical proof (experimentally verified by Jean Perrin in 1912) of the existence of atoms and molecules. Brownian motion was explained at the same time as Einstein by Marian Smoluchowski and a few years before by Louis Bachelier in 1900, with motivations related to financial mathematics;
the third article is even more important, because it represents Einstein's intuitive break with Newtonian physics. In On the Electrodynamics of Bodies in Motion, the physicist tackles the postulate of absolute space and time, as defined by Newton's mechanics, and the existence of ether, an interstellar medium. inert which had to support light like water or air support sound waves in their movements. This article, published in June, leads to two conclusions:the ether does not exist, and time and space are relative. The new absolute that Einstein constructs is detached from the quantitative value of these two notions, space and time, which nevertheless remain linked by the conservation through different reference frames of study of the space-time interval between events, a concept similar to the distance between points in space. The consequences of this revolutionary view of physics, which stemmed from Einstein's idea of how physical laws should constrain the universe, shook up both theoretical physics and its practical applications. The exact contribution of Einstein compared to Henri Poincaré and some other physicists is today quite disputed (see Controversy on the paternity of relativity);
the last article, published in September, gives the title Does the inertia of a body depend on its energy content? a famous answer:the mass-energy equivalence formula, E=mc2. It is a result of the very new special relativity, from which arises a vast field of study and application:nuclear physics, celestial mechanics, and nuclear weapons and power plants, for example.
Recognition years (1910-1935)
His former classmate Marcel Grossmann helped him in his work by providing him with his knowledge of differential geometry:they published an article on Ricci and Riemann-Christoffel tensors in 1913. In October 1914, Einstein published an article on differential geometry, and in June 1915 he lectured at Göttingen University before Hilbert and Klein.
In 1916, Einstein published his so-called theory of general relativity. The "field equations" are the keystone of this theory. They describe the behavior of the gravitational field (the metric of space-time) as a function of energy and material content. The theory of relativity together with his works of 1905 and 1916 form the basis of modern physics.
The theory of general relativity published, Einstein begins to work again on quantum physics and introduces in 1917 the notion of stimulated emission which allows him to find Planck's law from purely quantum hypotheses on the way in which quanta of light (photons) are absorbed and emitted by atoms. Fruitful idea which is the basis of the development of the maser and the laser. The same year, Einstein shows that it is advisable to associate a quantity of movement to the quantum of light; hypothesis which will be validated by experience in 1923 thanks to the work of Arthur Compton on the diffusion of X-rays.
Einstein's relationship with the then nascent quantum physics is remarkable:on the one hand, many of his works laid the foundation for the development of this new physics, such as his explanation of the photoelectric effect; on the other hand, he will criticize many ideas and interpretations of quantum mechanics, its non-determinism in particular. The debate between the group formed by Einstein and Erwin Schrödinger and that of Niels Bohr and Werner Heisenberg was at the border of physics and philosophy.
In 1927, invited to the fifth Solvay congress, he had numerous conversations with Niels Bohr on this subject. He then said:"Gott würfelt nicht" ("God does not play dice") to mark his opposition to the probabilistic interpretation of quantum physics, to which Niels Bohr replied:"Who are you Albert Einstein to say to God what should he do? ". The EPR paradox that he clarified in 1935 with Boris Podolsky and Nathan Rosen at Princeton remains today an important example of an attempt to question the foundations of quantum mechanics.
Verification by eclipse
To verify general relativity, a measurement of the deviation of light rays around a mass during a solar eclipse is considered. The first expedition was planned for 1915, but was made impossible by the First World War. In 1919, Arthur Eddington carried out this measurement and announced that the results were in accordance with Einstein's theory. It appears much later that due to the cloudy weather, the margin of error was much greater than the phenomenon to be measured. Physicist Stephen Hawking commented in 1988 in his book A Brief History of Time that this kind of false good result is common when you know what to expect. Since other measurements had in the meantime confirmed the deviation of light, the validity of general relativity was not undermined.
Einstein and politics
The political positions taken by Einstein are marked by his socialist and pacifist opinions, sometimes relativizing the latter, for example by advising against conscientious objection to a young European who wrote to him during the 1930s, "for the safeguard of his country and the civilization ". In 1913, he co-signed a petition for peace that three other German scholars agreed to sign. Einstein had a strong antipathy towards military institutions, publishing as early as 1934:
“The worst of gregarious institutions is called the army. I hate her. If a man can experience any pleasure in marching in line to the sounds of music, I despise this man... He does not deserve a human brain since a spinal cord satisfies him. We should eradicate this cancer of civilization as soon as possible. »
Einstein is linked to many pacifist causes, as he is open to the multiple offers of support he receives, and often agrees to commit to causes he deems just. Einstein gave strong support to Zionist movements. In 1920, he accompanied the Zionist leader Chaim Weizmann to the United States during a fundraising campaign. He also traveled to Mandatory Palestine as part of the inauguration of the Hebrew University of Jerusalem to which he later bequeathed his personal archives. His appearances lend political prestige to the Zionist cause. Following an invitation to settle in Jerusalem, he wrote in his travel diary that “the heart says yes […] but reason says no”. According to Tom Segev, Einstein appreciates his trip to Palestine and the honors bestowed on him. He nevertheless marks his disapproval when he sees Jews praying in front of the Wailing Wall; Einstein comments that these are people stuck in the past and ignoring the present. Ben Gurion offered him the presidency of the State of Israel in 1952, which he refused:
"First, if I know the laws of the universe, I know almost nothing about human beings. Also, it seems that a president of Israel sometimes has to sign things that he disapproves of, and no one can imagine that I can do that. »
This refusal is due to the fact that his health is declining, as well as to the vision he has of Israel, where he hoped to see a cohabitation between Jews and Arabs and not the establishment of a Jewish nation.
He has a far-sighted vision of his situation between the two wars. He writes in a remark at the end of an article written for the Times of London:
“I now pass in Germany for a German scholar and in England for a Swiss Jew. Suppose fate turns me into a nemesis, and on the contrary I will become a Swiss Jew in Germany, and a German scholar in England. »
He received death threats in 1922. Violent attacks took place against his theory of relativity in Germany and Russia. Philipp Lenard, "head of Aryan or German physics" attributes to Friedrich Hasenöhrl the formula E=mc2 to make it an Aryan creation. Einstein resigns, just in time, from the Prussian academy in 1933, and he is excluded from that of Bavaria. In March 1933, as honorary president of the League Against Anti-Semitism, he launched an appeal to the civilized peoples of the universe, trying "to awaken the conscience of all countries which remain faithful to humanism and to political freedoms”; in this appeal he protests against “acts of brutal force and oppression against all free-spirited people and against Jews, which are taking place in Germany. That year, Einstein was on a trip abroad, and he chose not to return to Germany, where Hitler took power in January. After a stay in Belgium, he declined an offer from France to host him as a professor at the Collège de France, and left for the United States, at Princeton.
On August 2, 1939, he signed a letter, written by physicists Léo Szilard and Eugène Wigner, intended for Roosevelt, which helped to initiate the Manhattan project22, this thwarting the original intention of the letter which was only intended to be preventive potential risks that recent scientific discoveries could cause (these would indeed allow the realization of "bombs of a new type and extremely powerful").
In 1945, when he understood that the United States was going to make the first atomic bomb in history, he took the initiative to write once again to Roosevelt to ask him to give up this weapon.
After the war, Einstein campaigned for global atomic disarmament, until the threshold of his death in 1955, when he confessed to Linus Pauling:"I made a big mistake in my life when I signed this letter [de 1939]. »
After the Second World War, his commitment to the Jewish communities and Israel is nuanced by his pacifist opinions. He prefaced the Black Book, a collection of testimonies on the extermination of Jews in Russia by the Nazis during the war. And in December 1948, he co-signed a letter condemning the Deir Yassin massacre committed by Israeli Irgun and Lehi fighters during the 1948 Palestine War.
During the Cold War, he spoke out against the arms race and called, for example with Bertrand Russell and Joseph Rotblat, on scientists for more responsibility, on governments for a common renunciation of the proliferation of atomic weapons and their use, and the peoples to seek other means of obtaining peace (creation of the Emergency Committee of Atomic Scientists in 1946, Russell-Einstein Manifesto in 1954). He has repeatedly expressed his belief in the need to create a world state.
Einstein spoke about his socialist beliefs in 1949, at the height of McCarthyism, in an essay entitled Why Socialism, published in the Monthly Review. It seems to him that the principle of the government of peoples by themselves, the fact of working for themselves, is more conducive to individual development than that of the exploitation of the great number by a minority. But he is disappointed by what he can learn from the Soviet Union, and he considers that the peoples must first engage in pacifism, in order to put in place favorable conditions for an evolution towards socialism. His correspondence reveals that he sees a rapprochement between McCarthyism and the events of the 1930s in Germany. He wrote to the judge in charge of the Rosenberg case asking for their pardon, and he helped many people who wanted to immigrate to the United States. Contacted by William Frauenglass, a high school English teacher suspected of communist sympathies, he wrote a text openly denouncing McCarthyism and encouraging intellectuals to resist what he described as "evil". The FBI is opening a file on him, available today on their website. Joseph McCarthy attacks Einstein in Congress by calling him "the enemy of America". His secretary, Helen Dukas, is suspected of espionage in the service of the USSR. The American media are virulent in their treatment of the case, and only a few personalities, like Bertrand Russell, come to his defense. The case was closed in 1954, no conclusive evidence having been brought to support these accusations.
Einstein and the fight against racial discrimination
After fleeing Nazi Germany, Einstein discovers, during his American exile, the extent of racial discrimination in the United States. Living in the middle of the black community of Princeton, he closely observes segregation and invests daily so that black children have access to knowledge.
Refusing to intervene in universities that practice racial segregation, Einstein nevertheless agrees to give a lecture at Lincoln University in 1946 where he declares:"I am passing through this establishment in the name of a worthwhile cause. . Indeed, people of color continue to be segregated from white people in the United States. This separation is not the result of a disease of colored people but of a disease of white people. It is unthinkable that I am silent about this. »
He became friends with the black singer Paul Robeson and became, alongside him, an activist for civil rights and the fight against racism. With Robeson, Einstein also militates in favor of the support of the United States to the Spanish republicans who fight Francoism; both quickly attract the wrath and hatred of FBI director J. Edgar Hoover, who considers them "enemies of the state".
While he is harassed by the FBI for his political positions, the black intellectual and founder of the NAACP (association for the defense and advancement of blacks), W. E. B. Du Bois, solicits the support of Einstein for his defense before the federal court which is about to convict him of high treason. Einstein immediately vouches for Du Bois, which embarrasses the judges and prevents an arbitrary conviction of the latter.
This aspect of his life has remained largely unrecognized and ignored by most of his biographers.
Social life
Although Einstein met a large number of major personalities of his time, in the scientific, political and artistic fields, leaving a very rich correspondence, he described himself as a true loner "who never belonged to any heart to the State, to the native country, to the circle of friends and not even to the family in the narrow sense of the term, but which has always felt with regard to all these connections a feeling never weakened of their being foreign. »
Among his famous relationships are a friendship with Queen Elizabeth of Belgium, with whom he played the violin, Arnold Berliner (en) whom he shows affection on his 70th birthday, George Bernard Shaw about whom he writes " one rarely finds men independent enough to notice the weaknesses and foolishness of their contemporaries, without being infected by them themselves” or Bertrand Russell.
Modest and thinking as for him that “Each one must be respected in his person and no one should be idolized. “, he was ironic about his fame and its effects:“It could well come from the unrealizable desire for many, to understand some ideas that I found, in a relentless struggle, with my weak forces. »
His first wife, Mileva Maric suffers from coxalgia, which makes her lame. She is also a brilliant young woman, a student of the Polytechnicum. She becomes pregnant when they are not yet married, and she gives birth at her parents' house in Serbia to a daughter, Lieserl. Einstein was very harsh with his next companion, Elsa (doubly his cousin).
He sees little of his son Hans-Albert who, as an adult, works in California. The mental health of his other son, Eduard, deteriorated sharply when he was twenty years old, and he had to be interned for the first time in Zurich in 1930. His father paid him a last visit in 1933. At first critical towards psychoanalysis, he refuses that his son Eduard follows a new psychoanalytic treatment [ref. necessary], but he ended up accepting the essence of Sigmund Freud's ideas. In 1933, he chose Sigmund Freud to publish an exchange of letters entitled Why War?.
Einstein and religion
Einstein wrote several texts dealing with the relationship between science and religion. In his article published in 1930, Einstein distinguished three forms of religion:
the first is due to fear and a misunderstanding of the causality of natural phenomena, hence the invention of supernatural beings;
the second is social and moral;
the third, which Einstein calls "cosmic religiosity", is a contemplation of the structure of the Universe. It is compatible with science and is not associated with any dogma or belief. Einstein claims to be religious, but only in that third sense he sees in the word religion.
When, in 1929, Rabbi Herbert S. Goldstein asked him, "Do you believe in God?" Einstein replies:
"I believe in Spinoza's God who reveals himself in the harmonious order of what exists, and not in a God who cares about the fate and actions of human beings. »
Einstein often used the word God, as in his famous formula "God is subtle, but not malicious", however the meaning he gave to this word is the subject of various interpretations. Une partie du clergé a considéré que les vues d’Einstein étaient compatibles avec la foi. À l’inverse, le Vatican dénonce alors « un authentique athéisme même s’il est dissimulé derrière un panthéisme cosmique ». Si Einstein rejette les croyances traditionnelles, il se distingue personnellement des athées et répète qu’il est « un non-croyant profondément religieux ». Une lettre manuscrite écrite en allemand un an avant sa mort, et adressée au philosophe Eric Gutkind (en), sera mise en vente sur e-Bay en octobre 2012 , Einstein y écrivit :
« Le mot Dieu n’est pour moi rien de plus que l’expression et le produit des faiblesses humaines, la Bible un recueil de légendes, certes honorables mais primitives qui sont néanmoins assez puériles. Aucune interprétation, aussi subtile soit-elle, ne peut selon moi changer cela. »
Einstein répondra d’ailleurs à un journaliste lui demandant s’il croit en Dieu :
« Définissez-moi d’abord ce que vous entendez par Dieu et je vous dirai si j’y crois. »
Un militant de l’athéisme comme Richard Dawkins considère également que la position d’Einstein était seulement de l’athéisme poétiquement embelli. Lors de la campagne d’affichage de slogans en faveur de l’athéisme sur les bus de Londres en 2008 (soutenue par Dawkins), une citation d’Einstein fut utilisée. Cela provoqua des protestations, car cette utilisation a tendance à assimiler Einstein à un athée.
Dans ses mémoires, le diplomate Harry Kessler mentionne le fait d’avoir assisté à un échange entre une de ses connaissances et Einstein. À la question « Professeur, est-ce vrai que vous êtes profondément religieux ? », Albert Einstein aurait répondu « Certainement, ça dépend des points de vue. Quand j’essaie de pénétrer avec nos moyens limités les secrets de la nature, on découvre derrière tous les rapports qu’on peut connaître quelque chose de très subtil, d’insaisissable, d’inexplicable. Ma religion, c’est le profond respect de ce qu’il y a au-delà des domaines que nous pouvons explorer. C’est ainsi en effet que je suis croyant ».
Einstein et la philosophie
Albert Einstein a lu les grandes œuvres de philosophie, notamment celle de Ernst Mach, qui eut une influence philosophique dans sa jeunesse, amenant le physicien à réfuter la conception mécaniste qui est à la base de l’acceptation de la mécanique classique. Albert Einstein marque son intérêt pour la vision de l’humanité que propose Friedrich Nietzsche[réf. nécessaire], et certaines idées présentes dans les réflexions de Spinoza. Il propose une nouvelle vision du monde moderne par ses travaux scientifiques comme par ses ouvrages non scientifiques. Ainsi, dans son ouvrage Comment je vois le monde publié en 1934, un an après son installation aux États-Unis, Albert Einstein présente sa vision de l’humanité, et pose la question de la place de la science vis-à-vis de l’humanité.
Les travaux d’Einstein ont en tout cas fait abandonner en philosophie l’idée d’un temps absolu dans lequel baignerait un espace qui en serait séparé. Cette position novatrice46 avait en son temps amené Bergson à le rencontrer.
Einstein et le judaïsme
Albert Einstein s’intéresse aux questions du sionisme et de l’antisémitisme durant l’entre-deux-guerres, surtout entre 1919 et 1930, où nous disposons de nombreux écrits attestant de ses positions sur ces questions.
Durant l’entre-deux-guerres, il se rend en Palestine pour participer à la création de l’Université Hébraïque de Jérusalem.
Einstein et les mathématiques
Albert Einstein étudia les mathématiques auprès de professeurs comme Hurwitz ou Minkowski, mais reconnaît dans ses Documents autobiographiques (Œuvres choisies) que son « intuition dans le domaine des mathématiques n’était pas assez forte pour distinguer avec sûreté ce qui est essentiel et fondamental du reste. (…) Mon intérêt pour la connaissance de la nature était réellement plus fort; et du temps de mes études, il ne m’était pas évident que l’accès à une connaissance plus approfondie des principes de la physique passe obligatoirement par les méthodes mathématiques les plus raffinées ».
D’ailleurs, Albert Einstein, en 1921, lors de la conférence berlinoise intitulée la géométrie et l’expérience (conférence considérée comme le texte épistémologique le plus important d’Einstein, selon l’étude de Michel Paty, Einstein philosophe), déclara des propos confirmant la « destitution » de la géométrie euclidienne :
« Pour autant que les propositions de la mathématique se rapportent à la réalité, elles ne sont pas certaines, et pour autant qu’elles sont certaines, elles ne se rapportent pas à la réalité. »
Cette prise de distance très significative chez Einstein, par rapport aux mathématiques, trouve son fondement comme, par exemple, dans un ouvrage de 1917, La Théorie de la relativité restreinte et généralisée mise à la portée de tous :la configuration géométrique/mathématique du monde devient elle-même quelque chose de relatif, dépendant de la distribution des masses et de leur vitesse.
Einstein et l’astrologie
Contrairement à la citation qui lui est attachée par de nombreuses publications, en particulier celle de l’astrologue Élizabeth Teissier, Einstein ne croyait pas en l’astrologie.
La citation apocryphe qui lui est attribuée est :« L’astrologie est une science en soi, illuminatrice. J’ai beaucoup appris grâce à elle et je lui dois beaucoup. Les connaissances géophysiques mettent en relief le pouvoir des étoiles et des planètes sur le destin terrestre. À son tour, en un certain sens, l’astrologie le renforce. C’est pourquoi c’est une espèce d’élixir de vie pour l’humanité. »
Ce faux a pour origine le Huters astrologischer Kalender de 1960, publié en 1959. La phrase a donc été forgée environ cinq ans après la mort d’Einstein.
Son opinion négative sur l’astrologie est exprimée dans une introduction écrite en 1951 pour l’ouvrage de Carola Baumgardt. Einstein rappelle que Kepler avait su accepter l’idée que l’expérience seule pouvait décider de la validité d’une théorie mathématique, aussi belle soit-elle. Il cite alors l’astrologie comme illustration, dans la pensée képlérienne, d’un reste de manière de penser animiste et téléologiquement orientée omniprésente dans les recherches « scientifiques » de l’époque.
Einstein et le végétarisme
Albert Einstein soutient la cause végétarienne. Il considère le végétarisme comme un idéal sans pourtant le pratiquer lui-même malgré quelques problèmes de conscience. Ses arguments se basent principalement sur des raisons de santé, mais il croit également à l’effet bénéfique du régime végétarien sur le tempérament des hommes. Un an avant sa mort, il décide de mettre en pratique ses idées et entame un régime végétarien.
Le cerveau d’Einstein
En 1978, le journaliste Steven Levy apprend par son employeur le journal New Jersey Monthly que le cerveau du savant aurait été conservé et lui demande de le récupérer.
Levy est accompagné par un cameraman durant sa quête et le film est diffusé dans les années 1990 à la télévision en France. Après une longue enquête, il le retrouve en effet à Wichita (Kansas), chez le pathologiste qui avait procédé à son extraction, le Dr Thomas Harvey. Cette information souleva l’intérêt des médias.
Le Dr Harvey déclara qu’il n’avait rien trouvé de particulier dans la structure physique du cerveau d’Einstein pouvant expliquer son génie. Mais de plus récentes études, parues notamment dans Science et Vie, concluent que le cerveau d’Einstein possédait un nombre élevé d’astrocytes. Selon le premier médecin autorisé à autopsier le cerveau d’Albert Einstein dans les années 1980, Marian Diamond, certaines zones de son cerveau, réservées aux tâches les plus hautes, possédaient une proportion de cellules gliales incroyablement élevée :« tout indique que les cellules gliales occupent une place déterminante dans le développement de l’intelligence ».
Dans Mythologies, Roland Barthes écrivit un texte au sujet du cerveau d’Einstein, en restituant les fantasmes que celui-ci anime :comment donc est le cerveau d’un génie ?
Il s’avère, et c’est là tout l’intérêt de la situation à en croire la plume de Barthes, que le cerveau du dit « génie » n’avait rien d’atypique.
Une étude approfondie de la structure du cerveau révèle également que la scissure de Sylvius présente une inclinaison particulière, augmentant la taille de la zone du raisonnement abstrait au détriment de la zone du langage, ce qui pourrait expliquer qu’Einstein n’ait su parler que très tard.
En 2014, le neurologue américain Terence Hines publie une étude qui remet en cause la méthodologie et les conclusions qui ont été tirées avec trop d’enthousiasme, faisant suite à d’autres controverses.
Inventions et brevets
Einstein a aussi inventé des appareils et déposé de nombreux brevets en collaboration avec des amis :
voltmètre ultrasensible :en 1908, avec Paul Habicht, il met au point un voltmètre capable de mesurer des tensions de l’ordre d’un dix-millième de volt. Ce « multiplicateur de potentiel Einstein-Habicht » est commercialisé à partir de 1912;
réfrigérateur :avec son ancien étudiant et ami Leó Szilárd, il crée plusieurs types de réfrigérateurs (un système à absorption, un système à diffusion et un système électromagnétique). Ce dernier système s’appuie sur une « pompe électromagnétique » qui est encore utilisée pour transporter le sodium dans les réacteurs à neutrons rapides à caloporteur sodium (2005). Ces réfrigérateurs n’ont pas été commercialisés;
appareil de correction auditive :un des quarante brevets déposés avec Leó Szilárd.
Divers
Un einstein est une unité de mesure égale au nombre d’Avogadro multiplié par l’énergie d’un photon (lumière) (c’est donc l’énergie d’une mole de photons).
Il existe un élément chimique nommé d’après Einstein :l’einsteinium.
2005 fut l’année mondiale de la physique, mais aussi l’année d’Einstein, en commémoration du centenaire de l’annus mirabilis.
La date de naissance d’Albert Einstein est également la journée de p.
La Maison d’Einstein se trouve à Berne en Suisse.
De nombreuses citations célèbres sont erronément attribuées à Einstein de façon fréquente.
« Insanity is doing the same thing over and over again and expecting different results » (« la folie consiste à faire la même chose encore et encore et à attendre des résultats différents »). Le véritable auteur de cette citation est Rita Mae Brown, dans Sudden Death.
Distinctions
1921 :Prix Nobel de physique
1929 :Médaille Max-Planck
1931 :Prix Jules-Janssen
1935 :Médaille Franklin
Articles scientifiques (sélection)
Zur Elektrodynamik bewegter Körper. In :Annalen der Physik 17/1905, pages 891–921; traduit en français (Gauthier-Villars 1925, réédition Gabay 2005) « Sur l’électrodynamique des corps en mouvement ».
Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt. In :Annalen der Physik 17/1905, p. 132–148; trad. « Un point de vue heuristique concernant la conception et la transformation de la lumière ».
Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig ? In :Annalen der Physik 18/1905, pages 639–641; traduit en français (Gauthier-Villars 1925) « L’inertie d’un corps dépend-elle de sa capacité d’énergie ? »
Zur Quantentheorie der Strahlung. In :Mitteilungen der Physikalischen Gesellschaft Zürich 18/1916 und Physikalische Zeitschrift 18/1917, p. 121 et ss.; trad. « Sur la théorie quantique du rayonnement ».
Über Gravitationswellen, Comptes-rendus de l’Académie des sciences de Prusse (Berlin), 1918, 154; trad. « Des ondes gravitationnelles ».
(avec Boris Podolsky et Nathan Rosen) Can Quantum Mechanical Description of Physical Reality Be Considered Complete ?, Physical Review, 15 mai 1935; trad. « La description de la réalité physique par la mécanique quantique peut-elle être considérée comme complète ? »
Par ailleurs, une sélection des œuvres d’Einstein, notamment ses articles scientifiques originaux, sont disponibles en traduction française commentée sous le titre Œuvres choisies aux éditions du Seuil/CNRS éditions, dans la collection Sources du savoir (6 volumes parus depuis 1989).
Françoise Balibar (ed.), Albert Einstein :physique, philosophie, politique, éditions du Seuil, (ISBN 978-2-02-039658-5). Livre de poche qui contient des « morceaux choisis » issus de la sélection précédente.
Autres œuvres
Albert Einstein :La théorie de la relativité restreinte et générale. (1916, édition française Gauthier-Villars 1956)
Pourquoi la guerre ? (1933) Rivages, 2005, , avec Sigmund Freud.
Comment je vois le monde. (1934, édition française Flammarion 1934), réédition Flammarion, 1989, collection Champs 183, (ISBN 978-2-08-081183-7). Essai politico-philosophique, où Einstein expose ses positions dans différents domaines :social, économique, politique, religieux, culturel et scientifique.
Albert Einstein &Leopold Infeld :L’Évolution des idées en physique. collection Champs, Flammarion (1993), (ISBN 978-2-08-081119-6). Au format poche, une histoire de la physique, de la mécanique de Newton jusqu’aux théories modernes (relativité, quanta), écrite en 1936 par Einstein et l’un de ses disciples à Princeton, pour financer le séjour de ce dernier.
Albert Einstein Pourquoi le socialisme ?
L’Institut technique de Californie (Caltech) publie, avec l’aide de l’université hébraïque de Jérusalem, l’intégrale des écrits d’Einstein, The Einstein Papers Project. C’est une édition plutôt destinée aux bibliothèques. (http://www.einstein.caltech.edu)